Single-blade propeller



Mar'e'h 13,1945, w. w. EVERTS 2,371,160

SINGLE-BLADE PROPELLER Filed NOV. 1, 1939 3 Sheets-Sheet 1 as Q WalterWEye-ris.

iMarc'h 13, 1945. w. w. EVERT-S 2,371,160

S INGLE-BLADE PROPELLER Filed Nov. 1, 1939 5 Sheets-Sheet 3 PatentedMar. 13,1945

SINGLE-BLADE PROPELLER Walter W. Everts. Baltimore, Md., assignor toEverel Propeller Corporation, Baltimore, Md., a corporation of MarylandApplication November 1, 1939, Serial No. 302,423

11 Claims. My invention relates to improvements in single-bladepropellers.

An important object of the invention is to Provide a single-bladepropeller which is particu-' larly well adapted for use upon air craft,but which is also adapted for use in connection with boats includingsurface, ships or submarines and fans used for ventilating purposes orthe like.

A further object of the invention is to provide a propeller of the abovementioned character, which is automatically actuated by the action ofcentrifugal force, to vary its pitch, as the pressure of the fluidmedium within which the propeller is operating varies.

A further'object of the invention is to provide a simplified pivotalmounting for the variable pitch propeller which will permit of thepropeller automatically finding its plane of rotation.

A further object of the invention is to provide means for accuratelybalancing the propeller statically, vertically and horizontally.

A further object of the invention is to provide means to balance thepropeller dynamically.

A further object of the invention is to provide a propeller of the abovementioned character, having its pivotal mounting enclosed and itsleading side covered.

A further object of the invention is to provide means to limit theswinging movement of the propeller for varyingits pitch.

Figure is a rear end elevation of the front n, a a

Figure 11 is an exploded perspective view of the coupling hub andassociated elements.

In the drawings, wherein for the purpose of illustration is shown apreferred embodiment of my invention, the numeral l0 designates asingleblacle propeller as a whole. The propeller includes a single blade[0' having a center-line Ill. The propeller blade Ill has a leadingsection II and a trailing section l2, whichare unbalanced, the trailingsection having the greater area. This propeller may be formed of anysuitable material, such as aluminum, an aluminum alloy, Bakelite, wood,or the like. The propeller is preferably formed integral and comprises ahub H, carrying a shank I2 upon'one side, which carries the blade Ill.The hub has a counterweight shank or member l3 integral therewith,arranged opposite the shank l2. The hub II has circularly curvedportions l4, extending radially beyond the shank l2 and counter-weightshank or member 13. The action ofcentrifugal force upon the blade l0 andcounter-weight shank or Other objects and advantages of the inventionwill beapparent during the course of the following description.

In the accompanying drawings forming a part or this application and inwhich like numerals are employed to designate like parts throughout thesame,

Figure l is a front elevation of a single-blade propeller embodying myinvention,

Figure 2 is a transverse section taken on' llne 2- -2 of Figure 1,

Figure 3 is a vertical section taken on lined-3 I of Figure 2, partsbroken away,

Figure 4 is a plan view or the propeller, parts broken away, i K

Figure 5 is a horizontal section taken on line 5-4) of Figure 1, IFigure 6 is a vertical section taken on line, 6-

of Figure 4,

Figure '7 is a front elevation of the propeller, partly diagrammatic,with the propeller horizontal,

Figure 8 is a plan view of the same, Figure 9 is a front elevation ofthe propeller,

. artly diagrammatic, showing the samevertical,

member I3, produces radial thrusts in opposite directions which arebalanced. The entire propeller is also substantially statically balancedboth horizontally and vertically.

The propeller hub II is provided with a central circular recess 15,receiving oppositely arranged bearing blocks or members I 6, having fiatinner faces I1 and cylindricall'y curved outer faces l8. Each bearingblock It has curved end flanges l9 and flat end faces 20. Each bearingblock it has a cylindrical recess 2|. Arranged within each cylindricalrecess 2i is a bearing sleeve 22, having a tapered opening 23, which iscircular in cross-section, and increases in diameter inwardly. Thisbearing, sleeve receives a bronze bushing 24, having an outer taperedwall 7 and an inner tapered opening or bore 25, which iscircular incross-section and increases in diameter inwardly. The bronze bushing 24is prefe'rably apertured for the passage of a lubricant. The bronzebushings receive preferably hollow pivot elements 26, which areexteriorly tapered to properly fit within the bronze bushings. The pivotelements are preferably formed integral with a coupling hub 21, which istubular, to receive the crank shaft 28 of the engine of .an aeroplane orthe like. The pivot elements 26 are diametrically oppositely arrangedwith respect to the coupling hub 21 and shaft 28 and their centrallongitudinal axes are in a line 2B. The

21 and disposed in a transverse plane at a right angle to the centrallongitudinal axis of the coupling hub 21. The line 26' is inclined ordiagonal with respect to the center line l. Lines l0 and 26' intersectand both pass through the center of the coupling hub 21. The numeral 29designates a washer or sealing ring, which fits within an annular recessor groove 30 formed in the inner face l1 and also rests against a flatshoulder or face 3|, formed upon the coupling hub 21. This washer orsealing ring surrounds the bronze bushing 24 and engages the inner endof the bearing sleeve 22, and extends across the meeting faces ofelements 22 and I8.

The bearing blocks l6 and associated elements are assembled upon thecoupling hub 21 and these assembled parts are inserted into the circularopening l5.

A disc 32 is arranged upon the rear side of the propeller hub II, andthis disc is provided upon' its inner face with an annular groove 33, toreceive the flanges l3. .This disc also has a center opening 34 which isslightly elliptical. .Disposed upon the front side of the propeller hubII is a companion disc 35, provided upon its inner face with an annulargroove 36, receiving the flanges l9. This disc has a center opening 31which is preferably circular. The discs 32 and 35 are connected by mainbolts 38, passing through openings 33v and formed in the discs 32 and 35re-. spectively. These bolts also pass through suitable openings formedin the propeller hub H. The main bolts carry tapered washers 4| at theirforward ends, and nuts 42, having any suitable means to lock-the nutsagainst accidental rotation. The discs 32 and 35 are further connectedby auxiliary bolts 44 ,and through openings in the propeller hub ll 43,passing through openings and carrying nuts at their forward ends, withany suitable means to prevent accidental unscrewing of these nuts. Theseveral bolts are so arranged with relation to each other that thepropeller remains substantially statically balanced, both horizontallyand vertically, and the central longitudinal axes of the bolts 38 are inalignment with the center line ill of the' propeller. Screws 44' passthrough openings in the discs 32 and 35 and engage in screw-threadedopenings 45 formed in the bearing blocks I 6.

The counter-weight shank or member I3 is provided with a longitudinallyextending bore 46, receiving a sleeve 41, preferably formed of metal.This sleeve is cylindrical and has its central longitudinal axis inalignment with the center line Ill. The sleeve 46 has transverseopenings 48 near its inner end to receive themain bolt 36-. The sleeve41 has its outer end portion counterbored and provided with internalscrew-threads 49, to engage with screw-threads 50, formed upon the outerenlarged end portion of a weight 5|.

This weight has a slot 52 at its outer end to.

receive a screw driver or the like for turning the same. The sleeve 41has its outer'end also exteriorly screw-threaded, as shown at 53, forengagement within a cap 54, internally screwthreaded. This cap has anopening 55 at its end for the passage of a screw driver or the like. A'set screw 56 has screw-threaded engagement within a screw-thre dedopening '51formed in' the cap 54-and this se screw has a reduced shank58, which is smooth, and extends through an .\opening 59 in the sleeve41. This reduced shank passes to the'interior of the sleeve 41 andclamps against the weight 5| to lock the weight in the selected adjustedposition. The propeller as orig inally made, is balanced statically bothhorizontally and vertically, as much as possible, but is ordinarily notin true balance and the accurate balancing of the propeller staticallyhorizontally, is effected by the adjustment of the weight 5|.

Means are also provided to accurately balance the propeller staticallyvertically, comprising bolts 60, held within openings 6| formed in thepropeller hub I I. These bolts. carry nuts '62 arranged within recesses63. Arranged beneath the nuts 62 are removable weight washers 63. Byusing a suitable number of these weight washers 63', the staticbalancing of the propeller vertically may be approximately effected. Thebolts 60 have their central longitudinal axes in alignment with thediagonal line or axis 26. The bolts 60 are provided at their outer endswith longitudinally extending screw-threaded openings receivingadjustable weight-screws 64, passing through caps 65, which arepreferably resilient. The weight-screws 64 are turned to accuratelyadjust the static balancing of the propeller vertically and theresilient caps 65 hold the weight-screws against accidental movement.

The numeral 66 designates a torque weight,

torque on a single-blade propeller. The moment i exerted by the weightof this torque weight is equal and opposite to the unbalancedaerodynamic torque moment, thereby making the propeller balanceddynamically. The weight of this torque weight is calculated by atheoretical formula. The propeller assembly-is balanced statically on abalance bloek with the propeller *in both a horizontal and verticalposition. When the balancing about these axes is completed, the torqueweightis mounted at the intersection of the two planes; one passingthrough the hub axis in a vertical plane and another plane perpendicularto it passing through the longitudinal blade axis III. the propeller outof static balance vertically after balance static considerationsarefinished, and then balances-the propeller when in motion.

The crank shaft 28 has its forward end tapered i and inserted within thetapered bore of the coupling hub 21, and the crank shaft has a reducedscrew-threaded portion 16, which receives there- -on, the rear endof atubular shaft e xtension H,

which rear end is internally threaded, as shown. The tubular shaftextension'1l is provided at its rear end with an exterior flange 12,to,engage with a lock nut'13, engaging within a screwthreadedcounter-bore 14, formed in the coupling hub 21. This lock nutpreventsthe accidental turning of the tubular shaft extension 1|: Thelock nut-is held against accidental unscrewing by a cotter pin 15 or'the like.

Arranged upon the front disc 35 is a cap 16, having a flange 11, securedto the bearing blocks l6 by screws 18 engaging/ within openings 18formed in the block l6. The screws J8 have the further function ofproperly locating the cap 16 upon the disc 35 so thatthe recesses 60will receive' the screws 44'. Additional bolts 8| are also employed tosecure-the cap to the disc 35. The opening 18 leads into the bearingrecess 2|, so that grease or. other lubricant may be fed into The torqueweight then throws upon its diagonal axis 26'. As stated, the opening 34is elliptical and the longitudinal axis of the ellipse is at a rightangle to the diagonal line or axis 20.

Operation The operation of the propeller is as follows: The propeller isdriven counter-clockwise,

' viewed from the front of the aeroplane, which is the practice in theUnited States. As soon as the propeller rotates, centrifugal force actsupon the propeller and tends to move it to a radial position. Thisaction of centrifugal force is opposed by the air thrust, which tends toswing the propeller forwardly so that the outer end of the blade l movesforwardly from the radial position and inwardly of the maximum sweep.These two opposing forces act against each other and the blade willassume a normal operating position between the extreme forward positionand the true radial position. When the blade is in the extreme forwardposition it is at the minimum pitch and when in the true radial positionit has the maximum pitch, due to centrifugal force. Assuming that theaeroplane is now flying at substantially sea level, the air thrust isthen at the maximum and the blade has moved forwardly about the surfaceof a cone, to assume the forwardmost position which will impart totheblade the minimum pitch. During this action of the blade, the centerline Ill of the blade travels about the surface of a cone; and thecenter of the cone is the line 26. The action or centrifugal forcetends'to move the blade rearwardly about the surface of the cone towardthe true radial position, thereby increasing the pitch of the blade. Asthe speed of the aeroplane increases, the air pressure acting upon theforward face of the blade tends to move the blade rearwardly about thesurface of a cone for increasing the pitch of the blade. Assuming thatthe propeller is being flown in level flight at 2,000 R. P. M., at sealevel, the propeller will then have the minimum pitch, with respect tothe pitches which it will have at increased elevations. the aeroplanenow rises to a considerably higher elevation, the air thrust acting uponthe propeller will be reduced, while the action of centrifugal forceremains the same and hence the action of centrifugal force will overcomethe air thrust upon the propeller blade, and the blade would be movedrearwardly about the surface of the.

cone, and thereby increasing the pitch of the propeller blade. Thisincreased pitch of the propeller blade will cause the propeller todrive, the aeroplane at an increased speed but the speed of rotation ofthe propeller will remain substantially constant.

When the air pressure upon the front face of th blade I0 is sufficientto overcome the action of centrifugal force, as when the aeroplane ismaking a nose dive, wardly beyond the radial position, and the pitch ofthe blade is increased over the maximum pitch which can be impartedto itdue to the action of centrifugal force, which would occur when the bladeis shifted by centrifugal force into a true radial position. i v

the blade I0 is shifted rear-' Theblade I0 is capable of beingshiftedabout the surface of thecone, as described within limits, to vary itspitch, and this shifting movement is limited by the tubular shaftextension ll engaging the annularbumper 02.

It is to be understood that the form of my invention herewith shown anddescribed is to be taken as a preferred example of the same and thatvarious changes in the shape, size, and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, what I claim is:

. 1. In a propeller, a rotary driving element having pivot elementsarranged radially thereof, said pivot elements having a commonlongitudinal axis, a single-blade propeller including a hub carrying ablade and counter-weight member, the

blade and counter-weight member being oppo-- sitely arranged and havinga, common center line which passesv through the center of the rotarydriving element, said hub having an opening to receive the rotarydriving element and its pivot elements, bearing devices arranged withinthe opening of the hub and secured to the hub and receiving the pivotelements, the common longitudinal axis of the pivot elements beingarranged perpendicularly to and intersecting'the axis of rotation of thedriving element and diagonally with respect to the center line of theblade, so that the blade turns upon the pivot elements and the centerline of the blade travels about the surface of a cone having the commonlongitudinal axis of the pivot elements as the center of the cone.

2. In a propeller, a rotary driving element having oppositely arrangedradial pivot elements having a common longitudinal axis, a single-bladepropeller including a hub carrying an oppositely arranged blade andcounter-weight member, said hub having an opening to receive the rotarydriving element and its pivot elements, bearing devices arranged withinthe opening of the hub for receiving the pivot elements, the commonlongitudinal axis of the pivot elements being arranged perpendicularlyto and intersecting the axis of I rotation of the driving element anddiagonally with respect to the longitudinal axis of the blade, so thatthe blade turns-about the pivot elements and its center line travelsabout the 'surface of a cone, discs arranged upon oppositesides of thepropeller hub, means for securing the discs to the propeller hub, andmeans for securing the discs to the bearing devices.

3. In a propeller, a rotary driving .elem'ent having oppositely arrangedradial pivot elements, a single-blade propeller including a hub carryingoppositely arranged blade and counterweight member, said hub having anopeningto receive the rotary driving element and its pivot elements,bearing devices arranged withi the opening of the hub for receiving thepivot elements, the

turning axes of the pivot elements being arranged secured to the leadingdisc, said driving element having a part extending into the cap and arub- '-ber bumper mounted within the cap to engage with said extendingpart of the rotary driving element to limit the movement of the blade{or changing its pitch.

4. In a propeller, the combination of a propeller shaft, a tubularcoupling hub to receive a portion of the propeller shaft, said couplinghub having .ppositely arranged radial pivot elements, a single-bladepropeller including a hub having an opening and a blade and acounter-weight member disposed upon opposite sides of the opening, theopening receiving the coupling hub and pivot elements, bearing devicesarranged within the opening of the propeller hub to receive the pivotelements, the turning axes of-the pivot elements being arrangeddiagonally with respect to the longitudinal axis of the blade, discsarranged upon opposite sides of the propeller hub, means for securingthe discs to the propeller hub and to the bearing devices, a cap securedto the leading disc, a rubber bumper held within the cap, a tubularshaft extensionadapted to have screwthreaded engagement with the end ofthe propeller shaft and engaging the coupling hub the tubular shaftextension being arranged to engage the rubber bumper, and a lock nuthavingscrewthreaded engagement with the coupling hub and engaging thetubular shaft extension.

5. Ina propeller, a coupling hub having oppositely arranged pivotelements rigidly secured thereto, a single-blade propeller having a hubprovided with an opening and opposed blade and counter-weight membersarranged upon opposite sides of the openingybearing blocks arrangedwithin the opening and fixedly secured to the hub, said bearing gblockshaving recesses, hearing sleeves within the recesses, tubular bushingswithin the bearing sleeves and receiving the pivot elements, sealingrings arranged between the free ends of the bearing sleeves and thecoupling hub, the pivot elements having their turning axes arrangedperpendicularly to and intersecting the axis of rotation of the drivingelement and diagonally with relation to the longitudinal axis of theblade; I

6. In a propeller, a rotary driving element, a single-blade propellerincluding opposed blade and counter-weight members arranged uponopposite sides of the axis of rotation of the rotary driving element,pivot means fixed upon the rotary driving element and serving to,connect the propeller with the rotary driving element, the fixed pivotmeans having its turning axis arranged diagonally with respect to thelongitudinal axis of theblade, the counter-weight member having alongitudinal bore, the center line of the bore being in alignment withthe center line of the counter-weight member, a sleeve held within thebore, a weight arranged within the sleeve and having screw-threadedengagement therewith, and means to lock the weight in the adjustedposition. l

7. In a propeller, a rotary driving element, a single-blade propellerincluding a hub having an opening and opposed blade and counter-weightmembers, pivot means fixed upon the rotary driving element, bearingdevices arrangedwithin the opening andreceiving the pivot meansfthepivot means having its turning axis arranged diagonally with relation tothe longitudinal axis of theblade, discs arranged upon opposite sides ofthe hub, transverse bolts connecting the discs andsecuring them to thehub, means to attach sleeve and screw-threaded to engage with theinternal threads of the sleeve, 8. cap having screw-threads to engagewith the exterior threads of the sleeve, and means to lock the weightand cap against accidental unscrewing.

' 8. In a propeller, a rotary driving element, a single-blade propellerincluding opposed blade and counter-weight members arranged uponopposite sides of the axis of rotation of the rotary driving element,fixed pivot means serving to connect the propeller vwith the rotarydriving element and having its turning axis arranged diagonally withrespect to the longitudinal axis 01' the blade so that the blade movesabout the surface of a cone, adjustable means to accurately balance thepropeller statically horizontally, and adjustable means to accuratelybalance the, propeller statically vertically. l

9. In a propeller, a rotary driving element, a single-blade propellerincluding opposed blade and counter-weight members arranged uponopposite sides of the axis of rotation of the rotary driving element,fixed pivot means serving to connect the propeller with the rotarydriving element and having its turning axis arranged diagonally withrespect to the longitudinal axis of the blade, a device to accuratelybalance the propeller statically horizontally and adjustable along thelongitudinal axis of the counter-weight mem-. ber, a device toaccurately balance the propeller statically vertically and adjustablealong the line which is diagonal with respect to the longitudinal axisof the counter-weight member, and a device to balance the propellerdynamically and including one of more weight plates arranged between thefirst named devices and detachably secured to the propeller. i 10. Apropeller construction comprising a propeller hub having an axialopening, a rotary driving element having a part extending through theopening, means for pivotally mounting said hub on said driving elementfor pivotal movement about an axis transverse to the axis of the andcounter-weight members arranged upon opposite sides of the axis ofrotation of the rotary driving element, pivot means fixed upon therotary driving element and serving to connect the propeller with therotary driving element, the fixed pivot means having its turning axisarranged diagonally with respect to the longitudinal axis of the blade,the counter-weight member having a longitudinal bore, the center line ofthe bore being in alignment with the center axially adjustably mountedin said bore.

WALTER w; EVERTS.

